Hemolytic uremic syndrome (HUS) is primarily a disorder of infants and young children and rarely occurs in adults. HUS may occur in women in the postpartum period or in women taking oral contraceptives. Cancer patients receiving mitomycin or cisplatin chemotherapy may also develop HUS. There is evidence to suggest a genetic susceptibility to the development of thrombotic microangiopathies in siblings.95–98
Prominent features of HUS include:
- acute renal failure, with a need for frequent hemodialysis
- severe hypertension
- gastrointestinal signs and symptoms
Microangiopathic hemolytic anemia is present in HUS, as in thrombotic thrombocytopenic purpura (TTP), but the thrombocytopenia is milder in HUS and neurologic abnormalities are not frequent.
Sheth and colleagues have shown that the most common neurologic manifestations are seizures, mainly generalized tonic-clonic convulsions, but occasionally focal ones.91 One study found seizures in approximately 40% of HUS patients observed.101
Etiologies and risk factors for seizures
As with TTP, seizures can be associated with HUS for several reasons:
- Vascular damage in cortical regions, creating a seizure focus or foci
- Metabolic imbalance (e.g., uremia, hyponatremia, fever)90,101–103
- Cerebral hemorrhage due to thrombocytopenia102
- Other concurrent factors that may cause seizures independently (e.g., infections, drugs such as cyclosporine A or FK506,100 connective tissue diseases, and cancer)
Evaluation and treatment
Seizure management and evaluation are the same as for TTP. An additional factor to consider in choosing an AED for a patient with HUS is how likely the drug is to be removed from plasma during hemodialysis (See Table: Risk of Drug Removal By Hemodialysis). Phenytoin is not significantly removed during hemodialysis, so no adjustment is needed. Twenty percent of lamotrigine is removed after 4 hours of hemodialysis. Phenobarbital, ethosuximide, and gabapentin need adjustment after dialysis (See Correction for drug loss during hemodialysis).
Adapted from: Browne TR. Renal disorders. In: Ettinger AB and Devinsky O, eds. Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;49-62.
With permission from Elsevier (www.elsevier.com).